Effect of dry grinding and leaching on polytypic structure of pyrophyllite

摘要: Abstract The polytypic structure of a purified pyrophyllite sample from Zalamea (Badajoz, Spain) and the structural alteration induced after dry grinding leaching were studied by means infrared spectroscopy, nitrogen adsorption, thermal analysis X-ray diffraction methods (reflection transmission). Simulated powder patterns, using preparations with random preferred orientations coefficients orientation g=1 g=3, compared experimental patterns. It was found that is in modification 1Tc (1AA-II, 1). As to those simulated diffractograms, diminished intensity 11l 02l reflections due translations along b axis. A short time caused further degradation diffractions. This leads disordered forms not formation monoclinic polytype as has been claimed previously. DTA showed temperature shift main endothermic peak grinding. fastest during first few minutes In addition, areas decreased increasing surface area ground silicate. These changes are related progressive delamination breakdown Prolonged grinding, up 30 min, created turbostratic-type drastic reduction particle size about 0.04 μm diameter 0.02 thickness, this being features. After mechanochemical original particles appears have reached limit. At longer times there an degree amorphization decrease reaggregation powder. Thus, behaviour strongly dependent on state material. polytypism discussed. results for other samples (Honami, Japan, former Yugoslavia, Venezuela Ukraine). concluded one-layer triclinic or more likely than two-layer variety.